The present invention relates in general to cylinder locks and in particular to a cylinder lock having a cylinder core provided with a coupling device for transferring the rotary movement of the cylinder core to an additional locking member.
Cylinder locks provided with coupling devices in the form of a coupling sleeve slidably mounted on a free end portion of the cylinder core for engaging a locking member, are used particularly in connection with turn knobs such as used commonly in America. This invention is concerned particularly with the arrangement of a locking shaft on the inner end of the cylinder core. This locking shaft serves for transmitting the rotary movement of the core of the cylinder to the turn knob and to a corresponding mechanical locking bolt. The cylinder lock of this invention operates in conventional manner with the aid of simple or multiple segmented pin tumblers but in principle also a different kind of locking mechanism can be used.
The aforementioned locking shaft is usually in the form of a flat metal rod which at one end is bent or bulged. The bent portion or the bulge engages into a slot of a plate which is connected by an annular nut to the coupling end portion of the cylinder core. For this purpose it is necessary that the coupling end of the cylinder core be provided with an outer thread so as to engage the inner thread of the annular nut. Moreover, a snap pin must be provided in order to hold the annular nut in position. The annular nut also performs the function of protecting the cylinder core against removal from the lock housing. This function however due to limitations of material strength of the nut, is performed only imperfectly. The machining of a thread on the coupling end of the cylinder core and the provision of the corresponding annular nut makes the manufacture of the prior art cylinder locks of this kind expensive and disadvantageous.
Furthermore, in conventional constructions of the cylinder locks of this kind it has been necessary to modify the coupling component parts such as the locking shafts so as to enable the installation in connection with different designs of turn knob locks. Depending on the kind of the employed turn knob or locking cylinder, the locking shaft must be arranged either in a horizontal or in a vertical position. In many types of cylinder locks it is also necessary to provide an idling motion for the cylinder core so that the rotary movement of the locking shaft amounts to 180.degree. for example when the cylinder core is rotated about 360.degree. (in order to enable the withdrawal of a key from the cylinder core after the completion of its rotary movement). For different settings of the cylinder core it has been known to stamp in the end face of the aforementioned annular nut toothlike recesses for engaging a springbiased snap pin provided on the cylinder core. The snap pin in this prior art arrangement fixes the annular nut in its angular position and serves as a stop member for the bent portion of the locking shaft. The provision of such stamped recesses however is also expensive in manufacture and makes the entire construction of the lock more complicated.